Patent Literature 1 proposes a related vehicle seat slide device including: a lower rail formed in an inverted U-shape in cross section, with left and right opening edges bent inward in opposite directions, thereby forming top walls parallel with a bottom wall; an upper rail provided at longitudinally opposite end portions thereof with main rollers which roll on the bottom wall and with which the upper rail moves along the lower rail; sub rollers provided near the main rollers; and a coil spring which upwardly biases the sub rollers and brings them into contact with the top walls, while using the reaction force the sub roller receives during this state to bring the main rollers into contact with the bottom wall.